I would run trace program to see which program/service is writing all this. Could it be a virus, or some program went bananas writing in the endless loop. Have you look inside error logs? Did you look at system monitor and see what program is active more than others? Basically you need to identify what does all the writing and stop it, I don't think it's normal operation no matter what. Many programs use .tmp files, but they're temporary and are deleted automatically, not sure about BD: bullets? brush paint? database?
